The proposed research will study the mechanism by which araC gene protein of the L-arabinose operon in Escherichia coli positively controls the operon. This will be done with in vivo studies on wild type and mutant cells, and with in vitro studies involving the regulatory region DNA and regulatory proteins. The studies involve the purification and study of DNA fragments containing the regulatory region of the arabinose operon. In addition, the proteins involved in the regulation of the operon, araC protein, cyclic AMP binding protein, and RNA polymerase are being purified and their mechanism of action is being investigated with binding studies, protein and nucleotide sequencing, and high resolution electron microscopy. BIBLIOGRAPHIC REFERENCES: Size Fractionation of Double-Stranded DNA by Precipitation with Polyethylene Glycol, John T. Lis and Robert Schleif, Nucleic Acids Research 2, 383-389 (1975). The Isolation and Characterization of Plaque-forming Arabinose Transducing Bacteriophage Lambda, J.T. Lis and R. Schleif, J. Mol. Biol. 95, 395-407 (1975).